Diversity of deciduousness and phenological traits of key Indian dry tropical forest trees

Abstract

Keywords:tropical dry forests / deciduousness / wood density / leaf mass per area / leaf strategy index Abstract • In seasonally dry tropical forests deciduousness (leaflessness) is an important strategy of trees to survive in water stress period during summer. Deciduousness is a reflection of interacted effect of seasonal drought, tree characteristics and soil moisture conditions.• The present study aims to document the diversity in leaf pheno-phases in terms of duration of deciduousness (which is reciprocal to growing season length), wood density, leaf mass per area (LMA) and leaf strategy index in 24 important tree species growing in the Vindhyan dry tropical forest in India.• On the basis of phenological observations, the tree species were categorized into two main groups: leaf exchanging species exhibiting overlapping periods of leaf fall and leaf flush, and deciduous species whose timings of leaf flush and leaf fall differ resulting in a time lag (deciduousness) between the completion of leaf fall and initiation of leaf flush. Presence of wide range of deciduousness duration (from ca. a week to 7 months) among dry tropical trees indicates large variations in their growing season length. In the tree species studied, as the duration of deciduousness increased, leaf flushing period decreased significantly but leaf fall period showed little variation.• Differing deciduousness in tree species exhibited substantial differences in their leafing (vegetative growth) pattern, as reflected by ratio of durations of leaf flush to leaf fall (leaf strategy index). Across different species, duration of deciduousness was significantly positively correlated with leaf strategy index, and significantly negatively correlated with both wood density and LMA.• Wide variations in deciduousness, leaf strategy index, wood density and LMA in the 24 species investigated indicate considerable functional diversity in tree species growing in Vindhyan dry tropical region. Variation in seasonal duration of deciduousness among species is reflections of differences in tree functional traits like stem wood density, leaf strategy index and LMA. Mots-clés :forêts tropicales sèches / défoliation / densité du bois / masse de feuilles par unité de surface / index de stratégie de la feuille Résumé -La diversité des défoliations et les traits phénologiques d'arbres clés de la forêt sèche tropicale indienne.• Dans les forêts sèches tropicales saisonnières, la défoliation est une stratégie importante des arbres pour survivre dans les périodes de stress hydrique durant l'été. La défoliation est un reflet de l'interaction entre la sécheresse saisonnière, les caractéristiques des arbres et les conditions d'humidité du sol.• La présente étude vise à documenter la diversité des phénophases des feuilles en termes, de durée de la défoliation (qui est réciproque à la durée de la saison de croissance), de densité du bois, de masse foliaire par unité de surface (LMA) et d'indice de stratégie des feuilles chez 24 importantes espèces d'arbres poussant dans la for...

<b>Vegetative and reproductive phenology of <I>Aquilaria malaccensis</I> Lam. (Agarwood) in Cachar District, Assam, India</b>

“…The species that greatly depend on rainfall for initiation of the leaf would also be expected to show rapid leaf growth in order to maximize photosynthetic activity during the rainy season (Reich 1995), and this type of behavior is quite common in plants growing in seasonally dry environments (Wright et al 2002). Leaf initiation in the early rainy season is attributed to the end of the long dry season and also due to the joint action of increasing day length and temperature (Kushwaha et al 2010). Rivera et al (2002) have implicated that increasing day length acts as the inducer of flushing which is relevant to the leaf phenology in A. malaccensis.…”

Tree specific traits affect flowering time in Indian dry tropical forest

“…In tropical tree species, SWD, LMA, annual deciduousness and LSI may vary due to variations in their growing conditions as a result of changes in climatic variables like temperature, precipitation and soil moisture availability (Swenson and Enquist 2007;Kushwaha et al 2010). Abiotic factors (e.g.…”

“…Boswellia serrata and Sterculia urens) are generally restricted to ridges/hill tops. Majority of other deciduous species are distributed widely from moist to dry microsites (Kushwaha et al 2010). The forest becomes lush green during rainy season due to the presence of fully expanded leaves of trees and shrubs and a dense herbaceous layer.…”

“…Detailed information on leaf phenology, annual deciduousness, LMA, SWD and LSI of the 24 tree species has been published elsewhere (Kushwaha et al 2010). Briefly, the deciduousness ranged 3-9 days in leaf-exchanging species, 30-56 days in \2-monthdeciduous species, 75-116 days in 2-4-month-deciduous species and 129-231 days in [4-monthdeciduous species (Table 1).…”

“…In Indian dry tropical forests, variation in tree functional traits (e.g. leaf mass per area, LMA; stem wood density, SWD; leaf strategy index, LSI; and annual deciduousness) significantly affect the leaf (vegetative) phenological patterns (Kushwaha et al 2010). LMA plays a significant role in inter-specific variation in relative growth rate (Garnier 1992) and has been found to be positively related to leaf life span (which is reciprocal to deciduousness) and negatively to photosynthetic rate per mass (Wright et al 2004).…”